tert-Butyl carbamate → 2-Amino-4-fluoropyridine

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

2-chloro-4-fluoropyridine (1.5 g, 11.40 mmol), tert-butyl carbamate (1.403 g, 11.97 mmol), CESIUM CARBONATE (7.43 g, 22.81 mmol) ,TRIS(DIBENZYLIDENEACETONE)DIPALLADIUM (0.418 g, 0.46 mmol) and 9,9-DIMETHYL-4,5-BIS(DIPHENYLPHOSPHINO)XANTHENE (0.528 g, 0.91 mmol) were suspended in 1,4-dioxane (28 ml) ,degased with argon and heated to 90 °C for 4 hours. After cooling the reaction was quenched with water and extracted with ethyl acetate ( x 2 ). The combined organic phases were washed with water , a saturated aqueous solution of brine , dried over magnesium sulfate , concentrated then purified by preparative HPLC using a Waters X-Bridge reverse-phase column (C-18, 5 microns silica, 19 mm diameter, 100 mm length, flow rate of 40 ml / minute) and decreasingly polar mixtures of water (containing 0.2% ammonium carbonate) and acetonitrile as eluent. The product was diluted in DCM (5 mL) and was added TFA (1.00 mL). After 15 minutes, the volatiles were evaporated. The residue was treated with aq NH3 30% and reevaporated.

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